1. Field of the Invention
The present invention relates to a separable circuit breaker, and in particular to an improved separable circuit breaker which is capable of separately forming a trip apparatus casing and a switching apparatus casing, thus easily assembling the same.
2. Description of the Background Art
As shown in FIG. 1, the conventional circuit breaker includes a casing 1 formed of an insulation resin material and a cover 2. The inner structure formed inside the casing 1 and the cover 2 is composed of a trip apparatus and a switching apparatus.
The trip apparatus includes a bimetal 3, and a heater 5 installed below the bimetal 3 and a heater 5 having a fixing core 4. The heater 5 is connected with a load terminal 6.
In addition, beside the bimetal 3, an armature 7, which is rotatable, is fixed to the wall of the casing 1 and has a protrusion (not shown).
At this time, the bimetal 3 and the armature 7 are formed in a multiple number, respectively. Here, three pairs are adapted in a three phase electrode structure.
A protrusion (not shown) is formed above the bimetal 3 and the armature 7, and the above-described protrusion is crossingly spaced-apart from a trip crossbar by a predetermined distance.
At this time, the plate-shaped protrusions 8a of the bimetal 3 and the armature 7, which protrusions correspond with each electrode, are formed in one side of the trip crossbar 8, and a protrusion (not shown) is formed in another side of the trip crossbar 8 for pushing a latch holder 9.
The switching apparatus includes a mechanism unit and a fixed contact 10 and a movable contact 11 which are operable in accordance with the operation of the trip apparatus.
The fixed contact 10 is attached on an upper surface of a fixing contactor 13 connected with a power terminal 12.
A holder 15 one side of which is engaged with a movable contactor 14 is connected with an elongated shaft 16.
At this time, the movable contactor 14 is upwardly and downwardly movable with respect to the fixing shaft 20 connected with a side plate 17, and a grid 18 is formed outside a movable space of the movable contactor 14.
The mechanism unit of the switching apparatus is formed to configure the bimetals 3 and the armatures 7 which are installed in the center electrode. In more detail, the mechanism unit is composed of a latch 19 which is upwardly and downwardly movable with respect to a latch pin 17a fixed to the side plate 17, and a latch holder 9 on end of which is engaged with the latch 19 and the other side of which is connected with the trip crossbar 8.
A toggle link 21 is installed in an upper side of the holder 15 and connected by the holder pin 15a, and an upper link 22 is installed, one side of which is connected with the toggle link 21 by a link pin 23 and the other side of which is connected with the latch 19 by the upper link pin 22a, so that the upper link 22 is movable in a predetermined direction.
At this time, the link pin 23 is engaged with a spring 25 connected with the lever 24, and a manually operable handle 26 is installed in the lever 24.
The thusly constituted conventional circuit breaker is an apparatus for preventing an over current in a low voltage housing system and has a switching function with respect to a load current and failed current and a feature that it is reused after a predetermined breaking operation.
In the normal operational state of the conventional circuit breaker, the current flowing sequences are as follows: the power terminal 12--&gt;the fixed contactor 13 --&gt;the movable contact 11--&gt;the movable contactor 14--&gt;the heater 5--&gt;the load terminal 6.
The operation of the conventional circuit breaker will now be explained when the over current or short circuit current which exceeds a rated current flows in the circuit breaker.
If an over current which exceeds a rated current flows in the circuit breaker, the bimetal 3 becomes curved, and the trip operation in which the trip crossbar 8 is pushed is slowly performed. If the short circuit current flows in the system, a strong magnetic field is formed by the fixing core 4, so that the lower portion of the armature 7 is quickly and downwardly moved due to the magnetic field force, and at the same time, the protrusion (not shown) formed in an upper portion of the armature 7 pushes the trip crossbar 8. The above-described operation is called the quick trip operation. Therefore, the trip operation is quickly performed.
When the trip crossbar 8 is pushed during the slow trip operation of the bimetal 3 and the quick trip operation of the armature 7, the trip crossbar 8 is rotated, and the latch holder 9 is pushed by the rotation of the trip crossbar 8, so that the latch 19 engaged with the latch holder 9 is released therefrom, and thus the upper link 22 and the toggle link 21 are curved by the elastic force of the spring 25.
As the upper link 22 and the toggle link 21 are curved, the holder 15 connected with the toggle link 21 and the movable contactor 14 connected with the holder 15 are quickly and upwardly moved, so that the fixed contact 10 and the movable contact 11 are opened.
At this time, since the holder 15 and the movable contactor 14 are coaxially connected, and the fixed contact 10 and the movable contact 11 are opened, other electrodes are opened by the shaft 16.
At this time, at the time when the fixed and movable contacts 10 and 11 are opened, a predetermined arc occurs in the fixed and movable contacts 10 and 11.
The above-described arc is absorbed by the grid 18, and the blocking operation is finished.
However, in the above-described conventional beaker, when changing the capacity or rated current, the entire circuit breaker should be changed, thus causing much inconvenience.